Continuous feed head drill assembly

ABSTRACT

Opposed pairs of piston and cylinder assemblies each have a drill stem chuck which can be engaged or disengaged from the drill stem. When drilling, the lower chuck engages the drill stem and the lower pair of pistons moves downwardly while the upper pair moves upwardly together with the upper chuck. When the pistons are fully extended, the lower chuck releases and the upper chuck engages the drill stem whereupon the piston movement is reversed. The chuck engaging the drill stem rotates so that continuous rotation and feed is accomplished. The reverse action withdraws the drill stem from the drill hole. The upper part of the tower is pivoted so that the lengths of drill pipe can be moved from the horizontal to the vertical and vice versa. Hold means are provided engageable with a length of drill stem to prevent same from dropping into the drill hole while raising and lowering the drill stem. Hydraulic means are provided to jar the string loose if it jams in the hole and a modulating valve assembly is provided to prevent excess pressure being applied to the rotating drill bit.

United States Patent Adamson [54] CONTINUOUS FEED HEAD DRILL ASSEMBLY Filed: Jan; 15, 1971 Appl. No.: 106,691

[52] US. Cl. ..l 73/7, 173/46 173/105, 173/139,173/149,,173/152 Int. Cl ..E2lb 5/00, E21b 19/08 Field of Search ..173/7, 43, 46, 149 152-159 l l l 5 8 1 References Cited UNITED STATES PATENTS 8/1909 Hutchings ..l73/l49 10/1965 Tucker .L ..l73/l49 FOREIGN PATENTS OR APPLICATlONS 25,450 6/1963 East Germany 173/149 ma q; 7/////////////A 7////////Q,4

Jan. 2, 1973 [57] ABSTRACT Opposed pairs of piston and cylinder assemblies each have a drill stern chuck which can be engaged or disengaged trom the drill stem. When drilling, the lower chuck engages the drill stem and the lower pair of pistons moves downwardly while the upper pair moves upwardly together with the upper chuck. When the pistons are fully extended, the lower chuck releases and the upper chuck engages the drill stem whereupon the piston movement is reversed. The chuck engaging the drill stem rotates so that continuous rotation and feed is accomplished. The reverse action withdraws the drill'stem from the drill hole. The upper part of the tower is pivoted so that the lengths of drill pipe can be moved from the horizontal to the vertical and vice versa. l-lold means are provided engageable with a length of drill stem to prevent same from dropping into the drill hole while raising and lowering the drill stem. Hydraulic means areprovided to jar the string loose if it jams in the hole and a modulating valve assembly is provided to prevent excess pressure being applied to the rotating drill bit.

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INVENTOR. 513x97 Hymn,

CONTINUOUS FEED HEAD DRILL ASSEMBLY This invention relates to new and useful improvements in continuous feed universal head drills. v

The drill assembly is adapted for drilling in any mineral and is also designed to use equipment for the taking of cores in any geological formation and can also be used to take cores in concrete or other substances.

Standard Diamond Drills used in the above mentioned locations are relatively heavy units with very heavy gear drives and heavy winching equipment which makes them too heavy in most instances for helicopter transport into remote areas.

Such drills are provided with relatively short stroke feed rams and at the end of each stroke, the drilling operation has to be stopped and the ram uncoupled from the chuck (usually with a hand wrench) whereupon it can be returned to its starting position where it must be rechucked before drilling can re-commence. It is evident therefore that considerable time is lost between the end and beginning of each stroke.

Furthermore, each time a section of drill stem is added to or taken out of the drill string, a hand wrench is required to uncouple or recouple these drill pipe sections. This is a time consuming operation and also damages the drill pipe.

All drills presently in the field are provided with a derrick or tripod to which a pulley or crown block is attached, the purpose of which is to pull the drill stem out of the hole or put it back down again. Such drills must also have heavy winches and also require a man to climb onto a platform superposed above the tripod to receive and direct the pipe lengths as they are being raised or lowered as the case may be. When the pipe or drill string is being raised or lowered, the drill head must be moved off the drill hole and must be realigned after this operation has been completed. These drills depend on the human element to determine whether the feed should be increased or decreased when the resistance to the bit rises or falls in unpredictable rock structure or for other reasons.

Jars or cable operated jarring devices are used to extricate jammed or wedged drill pipe again necessitating the relatively heavy winches.

The invention hereinafter to be described can be used to drill any formation whether direct diamond drilling is required or whether coring is required.

It eliminates the necessity of heavy drives and winches inasmuch as continuous rotation can take place during the raising and lowering of the drill string.

The present device also screws and unscrews all drill pipe connections under power and is capable of removing the entire length of drill stem from the hole on a continuous basis with the exception of uncoupling the various lengths under power.

The drill pipe may also be removed or replaced while being rotated continuously even during the couple or uncoupling operation and this feature alone shows a distinct advantage over conventional drilling equipment when drilling in caving or broken ground conditions can cause the drill pipe to freeze or jam in the drill hole if the rotation is stopped at any point for coupling and uncoupling.

However, if the drill stem should jam in the drill hole, a novel jarring device is utilized eliminating the usual heavy winch and jars.

The head of the present device hinges under power to lower or raise section of drill pipes from a horizontal to a drilling angle or vice versa and the head can be adjusted to place or receive the pipe from a supply pile at the most convenient angle to that pile. This hinging action also allows the pipe to be uncoupled at approximately three and one half feet from ground level for easy ground level removal of core barrels if coring is taking place. Furthermore the bottom of the head unit always remains in line with the drill hole thus requiring no realignment when drilling is resumed.

In summary, the drill hereinafter to be described has automated much of the normal hand labor required when using standard drills, is much ligher than conventional units thus permitting helicopter transport to remote areas and furthermore drills faster and farther per bit than conventional drills due to the constant rotation and the fact that a novel modulating valve assembly is provided which automatically prevents excess pressure being applied to the rotating drill bit.

With the consideration and inventive objects herein set forth in view, and such other or further purposes, advantages or novel features as may become apparent from consideration of this disclosure and specification, the present invention consists of the inventive concept which is comprised, embodied, embraced, or included in the method, process, construction, composition, arrangement or combination of parts, or new use of any of the foregoing, herein exemplified in one or more specific embodiments of such concept, reference being had to the accompanying Figures in which:

FIG. 1 is a side elevation of the drill assembly showing same horizontally in phantom.

FIG. 2 is a plan view of FIG. 1 showing the movement from side to side in a horizontal plane.

FIG. 3 is a front elevation of FIG. 1 showing the movement in a vertical plane;

FIG. 4 is an enlarged partially fragmentary view of the main portion of the invention.

FIG. Sis a side sectional elevation enlarged with respect to the remainder of the drawings, of the modulating valve assembly.

FIG. 6 is a front elevation of the jar assembly per se.

FIG. 7 is a schematic diagram of the hydraulic circuitry of the universal head drill.

In the drawings like characters of reference indicate corresponding parts in the different figures.

Proceeding therefore to describe the invention in detail, reference character 10 illustrates generally a support frame consisting of vertical members 11 and diagonal members 12.

Centrally located supporting structure collectively designated 13 is mounted upon a vertically situated trunion 14 by means of a clamp 15, said trunion being mounted in turn upon a horizontally located member 16 supported by the support structure 10.

A square cross section shaft 17 extends through the member 16 and is operatively connected to the supporting structure 13 so that rotation of this squared shaft causes the central supporting structure 13 together with associated components to be rotated, within limits, in a horizontal plane as shown in F IG. 3.

An hydraulically operated gear box 18 is secured to the other end of the squared shaft 17 for the aforementioned rotation.

Furthermore an hydraulic piston and cylinder assembly 19 is mounted upon the support frame and extends between a horizontally located sleeve 20 journalled within the fixed sleeve 21 which in turn is secured to the support frame 10 so that movement of the piston and cylinder assembly 19 in the direction of double headed arrow 22, moves the centrally located supporting structure 13 inwardly and outwardly with respect to the support frame 10.

The support frame 10 includes an upper portion 23 anda lower portion 24. These portions are connected together by means of an offset hinge assembly 25, by means of a hinge pin 26.

An hydraulic piston and cylinder assembly 27 extends between offstanding brackets 28 mounted upon the lower support structure 24 and the piston rod of this assembly 27 is in turn pivotally connected to brackets 29 on structure extending upwardly from the upper support structure 23. This means that extension and retraction of this piston and cylinder assembly 27 causes the upper portion 23 together with the associated structure which will hereinafter be described, to move from the vertical or axial aligned position with the lower support structure 24, to a position substantially at right angles thereto as shown in phantom in FIG. 1.

Mounted to the upper support structure 23 and extending upwardly therefrom is a pair of spaced and parallel piston and cylinder assemblies collectively designated 30A and 30B. Each of these assemblies includes a cylinder 31 having a piston 32 reciprocal therein attached to a piston rod 33 which extends upwardly through glands 34 in the upper end of the cylinders 31.

A plate 35 is secured to the upper ends of the piston rods 33 and an upper chuck component 36 is secured to the plate 33. Journalled coaxially within this plate 35 is a sleeve 37, upper and lower bearing assemblies 38 journalling the sleeve to the aperture within the plate.

The upper chuck component 36 is in turn secured to sleeve 37 and is rotatable therewith.

A source of power taking the form of an hydraulic motor 39 is mounted adjacent one of the piston and cylinder assemblies 30 and a gear 40 is rotated in either direction by this hydraulic motor. This gear in turn rotates a further gear 41 which in turn is secured to the cylinder 37 so that the motor rotates the sleeve 37 together with the chuck component 36 secured thereto.

Reference character 42 illustrates a length of drill stem screw threadably secured to a further length of drill stem 42A depending downwardly and this length of drill stem passes freely through the sleeve 37 and downwardly through the supporting structure 23 and 24.

In turn it is secured to a drill bit (not illustrated).

Secured to and extending downwardly from the lower supporting structure 24 are corresponding piston and cylinder assemblies 30C and 30D. These are identical in construction and although they are not sectioned, corresponding parts have been given similar reference characters with the exception that these reference characters have been primed.

Each chuck component 36 and 36', are similar in sleeve 37, 37' and rotatable therewith. Within the cylinder is a piston 44 in turn secured to a pair of jaw actuators 45 which are provided with inclined inner faces 46.

Corresponding jaws 47 are engageable around the drill stem length 42 and are provided with opposed inclined outer faces 48 which engage with the inclined faces 46 of the actuators. Springs react between the head 50 of the cylinder 43 and the actuators and normally maintain the actuators together with the piston 44, out of engagement with the jaws.

However, if hydraulic fluid is fed through port 51 on the underside of the piston, this forces the piston together with the actuators upwardly thus jamming the jaws into engagement with the drill stem 42.

The lower chuck component 36' is of similar construction although it is not sectioned in the accompanying drawings.

Reference to the hydraulic circuitry which will hereinafter be described, will show that the following sequence can take place automatically.

Assuming that the drill string is being lowered for drilling purposes, the lower length 42A is fed through the supporting structure, and through the lower chuck component 36'-. The opposed pistons 32 of the upper pair of piston and cylinder assemblies 30A and 30B are at the lower end of the cylinders 31 and the lower pistons (not illustrated) are at the upper ends of the corresponding cylinders 31. The chuck component 36' is actuated to grasp or jam the rod or drill stem length. Hydraulic oil under pressure is fed on one side of the pistons 32 and the corresponding pistons 32 (not illustrated) thus causing the pistons to move apart from one another as they move upwardly or downwardly respectively within the cylinders. The lower pistons, carrying the lower chuck 36', which is in operative connection with the drill stem length 42A, causes this drill stem length to move downwardly and the hydraulic motor 39' rotates this drill stem. The upper chuck component 36 is not engaged with the drill stem length 42 so that the pistons move this chuck component upwardly and freely. When the pistons reach the extremities of the cylinders, the valving is reversed, the lower chuck 36' is released and the upper chuck component 36 is actuated to grasp the upper I drill string length 42. Rotation is maintained by the hydraulic motor 39 and the pistons commence to move towards one another thus causing the drill stem length 42 to move downwardly and to be rotated in a continu ous basis. The lower chuck component 36 moves upwardly along the length 42A as it is not engaged with this stem length at this time.

Removal of the drill string is a reversal of this procedure and once again is accomplished automatically.

When it is desired to couple or uncouple adjacent lengths of drill stem, at the junction point indicated by the reference character 52, the upper portion together with the upper piston and cylinder assemblies 30A and 308 may be moved to the horizontal position shown in phantom in FIG. 1 whereupon the new length of drill stem may be fed manually from the usual pile (not illustrated) stored adjacent the drill rig. This section is then,

moved upwardly to the normal drilling position construction and include a cylinder 43, 43', secured to whereupon the upper chuck component 36 is actuated to grasp this length and motor 39 is rotated. to screw it into engagement with the length 42A.

Removal is accomplished by reversal of these actions, it being understood that hydraulic motors 39 and 39 are reversible in operation. When the length 42 has been unscrewed by the motor 39, from the length 42A, the hinging action being offset due to the brackets 25 and pin 26, lifts the portion 42 clear of the portion 42A so that no jamming occurs. I

It is of course necessary to prevent the remainder of the drill string from falling down the hole when lengths of drill stem are replaced and removed and in this connection l have provided drill stem hold means collectively designated 53 and shown in detail in FIG. 4.

It is situated within the centrally located support structure and consists of a pair of stem engaging jaws 54 partially surrounding the stem 42A and having levers 55 engaged by one end within recesses 56 within the jaws 54. These levers extend diagonally outwardly and downwardly and engage by the other ends within angles or shoulders 57 formed within the supporting structure.

Diagonally situated slots 58 are also formed within the supporting structure substantially at right angles to the levers 55 and a pin and spring component 59 extends between these slots 58 and the levers 55. The spring is connected to the levers by one end thereof and to a pin 60 by the other ends thereof, said pins being mounted within said slots which are provided with enlarged ends 61.

When in the position shown in FIG. 4, the jaws 54 are biased upwardly and into engagement with the drill stem 42A so that any down movement of this drill stem jams the jaws against the levers thus preventing further downward movement. However, if the pins 60 are moved to the upper ends of the slots 58, the springs move overcenter with respect to the levers 5S and release the jaws and prevent this downward movement which at this time, of course, is controlled by either of the chuck components 36 or 36.

Reference .to FIG. 5 will show a modulating valve assembly collectively designated 62 which is inserted with the hydraulic system as clearly shown in FIG. 7.

It consists of a hollow body 63 within which is reciprocal, a shuttle valve 64 having an adjusting portion 65 and a spring 66 reacting between portion 65 and a shoulder 67 within the body normally urging the shuttle rightwardly with respect to FIG. 5.

The other end of the shuttle valve 64 is in the form of a stem 67 which freely engages a modulating valve 68 also mounted within the hollow body 63 for reciprocal action. A spring 69 reacts between the end of the stem 67 and the interior of the shuttle valve 68 and normally urges this shuttle valve leftwardly with respect to FIG. 5 but against pressure of a further spring 70 reacting between an adjustable portion 71 and the other end of the modulating valve 68.

This modulating valve is movable between the port 72 connected to oil from the feed system and an unloading port 73 connected to the reservoir.

An inlet 75 also extends through the body to a drilling 76 communicating with the front of the shuttle valve 64. This inlet 75 is connected to oil which is at the working pressure of the hydraulic motors 39 and 39'.

Under normal circumstances, the system is in equilibrium as shown in FIG. 5. However, if the bit starts to jam and torque increases at the bit, there will be a rapid buildup of oil pressure at the motors which will reflect to the inlet port 75 and move the shuttle valve 64 leftwardly with respect to FIG. 5 inasmuch as this oil will react upon the head of this shuttle valve. The shuttle valve will will move against pressure of spring 66 which normally holdsthe shuttle valve in position. The amount of movement is directly related to the increased pressure in the motor circuit and because of this movement, the shuttle valve 64 exerts pressure on the spring 69 which in turn exerts pressure on the modulating valve 68 thus countering the pressure being exerted by spring which is exerting pressure on the modulating valve 68 from the opposite direction. A modulating effect is produced on valve 68 by this balancing out of the effect of the spring 70 and the spring 69. The valve 68 is a pressure regulating valve to control the feed pressures in the cylinders 30A, B, C and D. The oil from the feed system enters the valve at 72 as hereinbefore described and the pressure on this oil under normal drilling conditions is controlled by the pressure set on the valve 68 by the pressure set on the valve 68 by the adjustment 71 and the spring 70. When the pressure in the feed circuit exceeds the spring pressure of spring 70, the valve 68 is moved away from a seating 74 within the body and oil flows through port 72, through channels 75 within the sides of the valve 68 and out through the discharge port 73 to the supply tank or reservoir thus keeping the pressure in the feed circuit constant. If the bit jams, the feed pressure drops to zero due to the unloading effect of the modulating valve assembly.

A sudden fall in motor pressure will of course cause a rapid rise in feed pressure so a needle valve 76 has been situated within the inlet 75 to regulate a slow return of the piston or shuttle 64 and thus modulate the return of the feed pressure to normal.

As hereinbefore described, drill stem lengths can be separated from one another under power by clamping the top chuck component 36 to the drill section above the joint 52 to be uncoupled and holding this chuck stationary while the bottom chuck component 36 is clamped to the pipe length below the joint and then rotated in a clockwise direction with the upper piston and cylinder components 30A and 308 in a minimum lift setting. The reverse of this operation will recouple the drill pipe.

It should be noted although this is not illustrated that the upper cylinders 31 are provided with a slightly larger diameter than the lower cylinders 31' to compensate for the volume taken up the piston rods 33 thereby providing both upper and lower pistons with the same square inch capacity on the down strokes to maintain even drilling pressures.

Although also not illustrated, the upper cylinders 31 are provided with large capacity conduits which can be connected to both pumping units and accumulator (shown in the hydraulic circuitry) provides very rapid strokes to apply thrust to a jarring component shown in FIG. 6.

In this connection I have provided upwardly extending tubular supports 77 extending upwardly and connected to the plate 35 upon the upper ends of pistons 33. A head frame 78 is attached to these tubular supports and is apertured to surround the upper length of 428 of the drill string extending upwardly above the machine. A relatively heavy spring 79 is secured to a block 80 on the head frame and surrounds the lower end of the drill stem section 42A.

A collar 81 is secured to the drill stem above the head frame 78 and spaced therefrom and a reciprocating weight 82 surrounds the drill stem and is movable between the spring 79 and the collar 81.

The upper cylinders 31 are fed a large volume of oil which causes the pistons to move rapidly outwardly together with the head frame 78, spring 80 and the weight 82 resting on the spring. The energy imparted to the weight 82 and the spring '79 by this rapid transit, throws the weight up the drill stem until it strikes the anvil or collar 81 which is firmly secured to the drill stern. This energy in turn lifts the jammed drill string. The lower anvil or block 80 and spring 79 absorb the shock of the returning weight 82 at which time the pistons 32 return to the lowermost position and the cycle is repeated. Lifting pressure and radial thrust can also be applied constantly by the lower chuck component 36' and the lower hydraulic motor 39'.

This eliminates the necessity of heavy winches and the like normally used to extricate jammed or wedged drill pipes.

The hydraulic system is shown schematically in FIG. 7 and operates as follows:

The oil is supplied to the drill components by a hydraulic pump 83 having several stages, each stage operating its own system, i.e., the drill chuck motor.

The hydraulic oil from the pump 83 is pumped to the cylinders which feed the drill stem (these consist of two cylinders which are mounted back to back with two other cylinders, each set of two moving in the opposite direction to the other set) (one such set is shown at 84). This cylinder moves the drilling head 85 back or forth as the case may be and by means of a cable 86 actuates a switch at 87 by rotating a drum 88 which moves a nut 89 back or forth. This in turn closes an electric switch 90 which actuates a solenoid at either 91 or 92 depending on the down or up position of the ram 84. The solenoid moves the control arm of valve 93 which actuates the ram in cylinder 94 which in the drawing engages the plunger in valve 95.

Pressurized hydraulic oil from a separate stage of pump 83 enters the valves 95 and 96, a pressure regulating valve 97 and thence to activate the hydraulic chuck assemblies 36 and 36', which engage the drill rod 42. Valve 97 can be regulated to adjust the holding pressures of the hydraulic chucks. Valve 95 is shown with the pressure from valve 97 shut off by the plunger and the oil in the line to chuck 36 by-passed back through the plunger to the suction or supply tank side of the pump 83, Chuck 36 controlled by valve 95 is now in a released position. Valve 96 controlling the line to chuck 36 shows the line under pressure which would therefore be in an engaged position. This assembly has been designed so that the pressure is always maintained in the lines from valve 97, and one or both chucks are always engaged on the drill pipe for reasons of safety. Should the machine stop or be stopped the check valve at 98 will prevent any back flow of oil to the pump and the nitrogen or air accumulator at 99 will continue to maintain the pressure to the chucks holding the drill stem.

The ram in cylinder 94 after engaging valve and disengaging chuck 36 continues to move bracket 100 which in turn moves the control arms of valves 101 and 102 in opposite directions. This in turn moves the two pairs of back to back feed 30A, 30B, 30C and 30D cylinders, with their respective chucks 36 and 36 in opposite directions and continuous feeding is affected. A torque-feed control valve 103 modulates the pressures in lines 104 and 105 to the feed cylinders as the pressure in the line to the radial drill motor 106 rises or falls. The check valves 107 and 108 prevent a reverse flow of oil into lines 104 or 105,-allowing the pair of cylinders which are feeding at that time to use the valve effectively and individually.

Manual or individual control can be effected by swinging the bracket 100 out of engagement with valves 101, 102, 96 and 95 and using hand levers as shown attached to valves 101 and 102.

While the hydraulic control mechanism has been described and illustrated as a combination of electric, hydraulic and .mechanical systems, nevertheless it should be understood that any one or a combination of systems can be used as desired.

Various modifications can be made within the scope of the inventive concept which is herein disclosed and/or claimed.

What I claim as my invention is:

1. A head drill used in conjunction with a source of hydraulic power and a length of drill stem forming a drill string; comprising in combination a support frame, centrally located supporting structure on said frame, an upper pair of piston and cylinder assemblies mounted on said supporting structure and a lower pair of piston and cylinder assemblies also mounted on said supporting structure in axial opposition to said upper pair, an upper drill stem chuck component mounted on the piston rods of said upper piston and cylinder assemblies and a corresponding lower drill stem chuck component mounted on the piston rods of said lower piston and cylinder assemblies, a source of power for selectively rotating each of said chuck components independently and in either direction, and means for engaging and disengaging either of said chuck components from the as sociated drill stem and drill stem hold means on said supporting structure selectively engageable with the length of drill stem between said lower piston and cylinder assemblies to prevent same from dropping downwardly into the associated drill hole while raising or lowering said drill string.

2.-The device according to claim 1 in which said hold means includes at least two opposing jaws engageable around said drill stem, a lever extending diagonally outwardly and downwardly between each of said jaws and said supporting structure, diagonally situated slots in said supporting structure situated approximately at right angles to said levers and a pin and spring component. extending between said levers and said slot whereby when said pin and spring component is in the lowermost position, downward movement of said drill stem is prevented by said jaws and when in the uppermost position, downward movement of said drill stem is permitted.

3. The device according to claim 2 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.

4. The device according to claim3 which includes a modulating valve in the hydraulic system operating said head drill, said valve reacting to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressure on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal on said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a .by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulicmotors.

5. The device according to claim 4 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said drill stem between said spring and said collar, upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stem against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity.

6. The device according to claim 1 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuatorsbeing mounted for relative movement in said cylinder, a

piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston inbuilt up from increased torque at the associated bit thereby modulating the feed pressures on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal in said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulic motors.

8. The device according to claim 7 which includes jar meansmounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stern spaced above said spring and a weight reciprocal on said drill stem between said spring and said collar, 'upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stern against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity.

9. A head drill used in conjunction with a source of hydraulic power and a length of drill stem forming a drill string; comprising in combination a support frame, centrally located supporting structure on said frame, an upper pair of piston and cylinder assemblies mounted on said supporting structure and a lower pair of piston and cylinder assemblies also mounted on said supporting structure in axial opposition to said upper pair, an upper drill stem chuck component mounted on the piston rods. of said upper piston and cylinder assemblies and a corresponding lower drill stem chuck component mounted on the piston rods of said lower piston and cylinder assemblies, a source of power for selectively rotating each of said chuck components independently and in either direction, and means for engaging and dis engaging either of said chuck components from the associated drill stem, and an offset transverse hinge,-

means on said supporting structure between said upper and lower piston and cylinder assemblies and a piston and cylinder assembly operatively extending between said supporting structure below said hinge means and said upper piston and cylinder assemblies whereby said supporting structure above said hingemeans together with said upper pair of piston and cylinder assemblies and said upper chuck component may be moved from a position in axial alignment with said lower piston and cylinder assemblies to a position substantially at right angles thereto for ease of removal and installation of lengths of drill stem upon said associated drill string.

10. The device according to claim 9 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components. I

11. The device according to claim 9 which includes drill stem hold means on said supporting structure selectively engageable with the length of drill stem between said lower piston and cylinder assemblies to prevent same from dropping downwardly into the associated drill hole while raising or lowering said drill string.

12. The device according to claim 11 in which said hold means includes at least two opposing jaws engageable around said drill stem, a lever extending diagonally outwardly and downwardly between each of said jaws and said supporting structure, diagonally situated slots in said supporting structure situated approximately at right angles to said levers and a pin and spring component extending between said levers and said slot whereby when said pin and spring component isin the lowermost position, downward movement of said drill stem is prevented by said jaws and when in the uppermost position, downward movement of said drill stem is permitted.

13. The device according to claim 11 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components. t

15. The device according to claim 13 which includes a modulating valve. in the hydraulic system operating said head drill, said valve reacting to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressures on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal in said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulic motors.

' 16. The device according to claim 15 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said drill stem between said collar, upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stem against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity.

17. A head drill used in conjunction with a source of hydraulic power and a length of drill stem fomiing a drill string; comprising in combination a support frame, centrally located supporting structure on said frame, an

upper pair of piston and cylinder assemblies mounted on said supporting structure and a lower pair of piston and cylinder assemblies also mounted on said supporting structure in axial opposition to said upper pair, an upper drill stem chuck component mounted on the piston rods of said upper piston and cylinder assemblies and a corresponding lower drill stem chuck component mounted on the piston rods of said lower piston and cylinder assemblies, a source of power for selectively rotating each of said chuck components independently and in either direction, and means for engaging and disengaging either of said chuck components from the associated drill stem, said upper and lower drill stem chuck components each including at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.

18. The device according to claim 17 which includes a modulating valve in the hydraulic system operating said head drill, said valve reacting to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressures on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal in said body, an

, inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-passconnection thereby reducing the oil pressure supply to said hydraulic motors.

19. The device according to claim 17 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stern and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said stem between said spring and said collar, upward against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity. 

1. A head drill used in conjunction with a source of hydraulic power and a length of drill stem forming a drill string; comprising in combination a support frame, centrally located supporting structure on said frame, an upper pair of piston and cylinder assemblies mounted on said supporting structure and a lower pair of piston and cylinder assemblies also mounted on said supporting structure in axial opposition to said upper pair, an upper drill stem chuck component mounted on the piston rods of said upper piston and cylinder assemblies and a corresponding lower drill stem chuck component mounted on the piston rods of said lower piston and cylinder assemblies, a source of power for selectively rotating each of said chuck components independently and in either direction, and means for engaging and disengaging either of said chuck components from the associated drill stem and drill stem hold means on said supporting structure selectively engageable with the length of drill stem between said lower piston and cylinder assemblies to prevent same from dropping downwardly into the associated drill hole while raising or lowering said drill string.
 2. The device according to claim 1 in which said hold means includes at least two opposing jaws engageable around said drill stem, a lever extending diagonally outwardly and downwardly between each of said jaws and said supporting structure, diagonally situated slots in said supporting structure situated approximately at right angles to said levers and a pin and spring component extending between said levers and said slot whereby when said pin and spring component is in the lowermost position, downward movement of said drill stem is prevented by said jaws and when in the uppermost position, downward movement of said drill stem is permitted.
 3. The device according to claim 2 in which said upper and lower drill stem chuck components each inCludes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.
 4. The device according to claim 3 which includes a modulating valve in the hydraulic system operating said head drill, said valve reacting to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressure on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal on said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulic motors.
 5. The device according to claim 4 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said drill stem between said spring and said collar, upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stem against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity.
 6. The device according to claim 1 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.
 7. The device according to claim 6 which includes a modulating valve in the hydraulic system operating said head drill, said valve reactinG to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressures on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal in said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulic motors.
 8. The device according to claim 7 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said drill stem between said spring and said collar, upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stem against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity.
 9. A head drill used in conjunction with a source of hydraulic power and a length of drill stem forming a drill string; comprising in combination a support frame, centrally located supporting structure on said frame, an upper pair of piston and cylinder assemblies mounted on said supporting structure and a lower pair of piston and cylinder assemblies also mounted on said supporting structure in axial opposition to said upper pair, an upper drill stem chuck component mounted on the piston rods of said upper piston and cylinder assemblies and a corresponding lower drill stem chuck component mounted on the piston rods of said lower piston and cylinder assemblies, a source of power for selectively rotating each of said chuck components independently and in either direction, and means for engaging and disengaging either of said chuck components from the associated drill stem, and an offset transverse hinge means on said supporting structure between said upper and lower piston and cylinder assemblies and a piston and cylinder assembly operatively extending between said supporting structure below said hinge means and said upper piston and cylinder assemblies whereby said supporting structure above said hinge means together with said upper pair of piston and cylinder assemblies and said upper chuck component may be moved from a position in axial alignment with said lower piston and cylinder assemblies to a position substantially at right angles thereto for ease of removal and installation of lengths of drill stem upon said associated drill string.
 10. The device according to claim 9 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic Fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.
 11. The device according to claim 9 which includes drill stem hold means on said supporting structure selectively engageable with the length of drill stem between said lower piston and cylinder assemblies to prevent same from dropping downwardly into the associated drill hole while raising or lowering said drill string.
 12. The device according to claim 11 in which said hold means includes at least two opposing jaws engageable around said drill stem, a lever extending diagonally outwardly and downwardly between each of said jaws and said supporting structure, diagonally situated slots in said supporting structure situated approximately at right angles to said levers and a pin and spring component extending between said levers and said slot whereby when said pin and spring component is in the lowermost position, downward movement of said drill stem is prevented by said jaws and when in the uppermost position, downward movement of said drill stem is permitted.
 13. The device according to claim 11 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.
 14. The device according to claim 12 in which said upper and lower drill stem chuck components each includes at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.
 15. The device according to claim 13 which includes a modulating valve in the hydraulic system operating said head drill, said valve reacting to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressures on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal in said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spRing normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed system of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulic motors.
 16. The device according to claim 15 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said drill stem between said collar, upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stem against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity.
 17. A head drill used in conjunction with a source of hydraulic power and a length of drill stem forming a drill string; comprising in combination a support frame, centrally located supporting structure on said frame, an upper pair of piston and cylinder assemblies mounted on said supporting structure and a lower pair of piston and cylinder assemblies also mounted on said supporting structure in axial opposition to said upper pair, an upper drill stem chuck component mounted on the piston rods of said upper piston and cylinder assemblies and a corresponding lower drill stem chuck component mounted on the piston rods of said lower piston and cylinder assemblies, a source of power for selectively rotating each of said chuck components independently and in either direction, and means for engaging and disengaging either of said chuck components from the associated drill stem, said upper and lower drill stem chuck components each including at least one pair of stem engaging jaws, said jaws having inclined outer surfaces, a jaw actuator for each of said jaws having an inner inclined surface opposite to said outer inclined surface of said jaw and engageable therewith, a cylinder, said jaws and said actuators being mounted for relative movement in said cylinder, a piston also in said cylinder and connected to said actuators, a source of hydraulic fluid to move said piston in said cylinder thereby to engage said actuators with said jaws and jam same into locking engagement with said drill stem, and spring means reacting between the head of said cylinder and said actuator normally biassing said actuator out of engagement with said jaws, said source of power for said chuck component taking the form of an hydraulic motor operatively connected to each of said chuck components.
 18. The device according to claim 17 which includes a modulating valve in the hydraulic system operating said head drill, said valve reacting to hydraulic pressure built up from increased torque at the associated bit thereby modulating the feed pressures on said piston and cylinder assemblies, said valve including a hollow body, a main shuttle valve reciprocal in said body, an inlet in said body to one side of said shuttle valve, said inlet being operatively connected to said source of hydraulic pressure for said chuck components, a first adjustable spring normally biassing said shuttle against movement by the pressure of oil in said inlet, a control valve piston also reciprocal in said body, a second adjustable spring normally biassing said piston towards said shuttle valve, a third spring between said shuttle valve and said piston, a first connection to said body from the feed systEm of said source of power on one side of said piston, and a by-pass connected on the other side of said piston whereby excess pressure in said inlet generated by increased torque of the associated bit, moves said shuttle and hence said piston in one direction to form a connection between said first connection and said by-pass connection thereby reducing the oil pressure supply to said hydraulic motors.
 19. The device according to claim 17 which includes jar means mounted on the upper end of said upper piston and cylinder assemblies for breaking loose jammed drill strings, said jar means including a head frame secured to the cylinders of said upper piston and cylinder assemblies, a spring surrounding the associated drill stem and engaging said head frame, a collar fixedly attachable to said associated drill stem spaced above said spring and a weight reciprocal on said stem between said spring and said collar, upward movement of said upper piston and cylinder assemblies throwing said weight upwardly on said drill stem against said collar for upward jarring action on said drill string, said spring absorbing kinetic energy from said weight when same moves downwardly by gravity. 